Development of a large maritime reconnaissance and bombing flying-boat was initiated by the Beriev design bureau in 1943, and the Beriev LL-143 prototype flew for the first time on 6 September 1945. An all-metal high-wing monoplane, it was powered by two 1492kW Shvetsov ASh-72 radial engines. Armament comprised twin NS-23 23mm cannon in a tail turret (behind the twin fins and rudders) and similar provision in a remotely controlled dorsal barbette. A single NS-23 cannon was installed in the bow turret.